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.\" $Id: dwarf_get_fde_list.3 3962 2022-03-12 15:56:10Z jkoshy $
.\"
.Dd November 9, 2011
.Dt DWARF_GET_FDE_LIST 3
.Os
.Sh NAME
.Nm dwarf_get_fde_list
.Nd retrieve frame information
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_get_fde_list
.Fa "Dwarf_Debug dbg"
.Fa "Dwarf_Cie **cie_list"
.Fa "Dwarf_Signed *cie_count"
.Fa "Dwarf_Fde **fde_list"
.Fa "Dwarf_Signed *fde_count"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_get_fde_list_eh
.Fa "Dwarf_Debug dbg"
.Fa "Dwarf_Cie **cie_list"
.Fa "Dwarf_Signed *cie_count"
.Fa "Dwarf_Fde **fde_list"
.Fa "Dwarf_Signed *fde_count"
.Fa "Dwarf_Error *err"
.Fc
.Sh DESCRIPTION
These functions retrieve frame related information for the specified
DWARF debug context.
.Pp
Function
.Fn dwarf_get_fde_list
retrieves frame information from the DWARF section named
.Dq ".debug_frame" .
For objects containing GNU style C++ exception handling
information, the function
.Fn dwarf_get_fde_list_eh
retrieves frame information from the section named
.Dq ".eh_frame" .
.Pp
Frame information is returned using opaque descriptors
of type
.Vt Dwarf_Cie
and
.Vt Dwarf_Fde .
Applications need to use the other frame related functions in the
DWARF(3) API set to retrieve the information contained in these
descriptors.
.Pp
Argument
.Fa dbg
should reference a DWARF debug context allocated using
.Xr dwarf_init 3 .
.Pp
Argument
.Fa cie_list
should point to a location that will be set to a pointer to an array
of
.Vt Dwarf_Cie
descriptors.
.Pp
Argument
.Fa cie_count
should point to a location that will be set to the number of
.Vt Dwarf_Cie
descriptors returned.
.Pp
Argument
.Fa fde_list
should point to a location that will be set to a pointer to an array
of
.Vt Dwarf_Fde
descriptors.
.Pp
Argument
.Fa fde_count
should point to a location that will be set to the number of
.Vt Dwarf_Fde
descriptors returned.
.Pp
If argument
.Fa err
is not
.Dv NULL ,
it will be used to store error information in case of an error.
.Ss Memory Management
The memory areas used for the arrays returned in arguments
.Fa cie_list
and
.Fa fde_list
are owned by the
.Lb libdwarf .
Application code should not attempt to directly free these areas.
Portable applications should instead use the
.Xr dwarf_fde_cie_list_dealloc 3
function to indicate that these memory areas may be freed.
.Sh RETURN VALUES
On success, these functions returns
.Dv DW_DLV_OK .
They return
.Dv DW_DLV_NO_ENTRY
if there is no frame information associated with the given DWARF
debug context.
In case of an error, they return
.Dv DW_DLV_ERROR
and set the argument
.Fa err .
.Sh EXAMPLES
To obtain frame information from the
.Dq ".debug_frame"
section, use:
.Bd -literal -offset indent
Dwarf_Debug dbg;
Dwarf_Cie *cie_list, cie;
Dwarf_Fde *fde_list, fde;
Dwarf_Off fde_offset, cie_offset;
Dwarf_Unsigned func_len, fde_length, fde_instlen;
Dwarf_Signed cie_count, fde_count, cie_index;
Dwarf_Addr low_pc;
Dwarf_Ptr fde_addr, fde_inst, cie_inst;
Dwarf_Error de;
int i;

if (dwarf_get_fde_list(dbg, &cie_list, &cie_count,
    &fde_list, &fde_count, &de) != DW_DLV_OK) {
	errx(EXIT_FAILURE, "dwarf_get_fde_list failed: %s",
	    dwarf_errmsg(de));
}

for (i = 0; i < fde_count; i++) {
	if (dwarf_get_fde_n(fde_list, i, &fde, &de) != DW_DLV_OK) {
		warnx("dwarf_get_fde_n failed: %s",
		    dwarf_errmsg(de));
		continue;
	}
	if (dwarf_get_cie_of_fde(fde, &cie, &de) != DW_DLV_OK) {
		warnx("dwarf_get_fde_n failed: %s",
		    dwarf_errmsg(de));
		continue;
	}
	if (dwarf_get_fde_range(fde, &low_pc, &func_len, &fde_addr,
	    &fde_length, &cie_offset, &cie_index, &fde_offset,
	    &de) != DW_DLV_OK) {
		warnx("dwarf_get_fde_range failed: %s",
		    dwarf_errmsg(de));
		continue;
	}
	if (dwarf_get_fde_instr_bytes(fde, &fde_inst, &fde_instlen,
	    &de) != DW_DLV_OK) {
		warnx("dwarf_get_fde_instr_bytes failed: %s",
		    dwarf_errmsg(de));
		continue;
	}

	/* ... Use the retrieved frame information ... */
}

/* Indicate that the returned arrays may be freed. */
dwarf_fde_cie_list_dealloc(dbg, cie_list, cie_count, fde_list,
    fde_count);
.Ed
.Sh ERRORS
These functions may fail with the following errors:
.Bl -tag -width ".Bq Er DW_DLE_ARGUMENT"
.It Bq Er DW_DLE_ARGUMENT
One of the arguments
.Va dbg ,
.Va cie_list ,
.Va cie_count ,
.Va fde_list
or
.Va fde_count
was
.Dv NULL .
.It Bq Er DW_DLE_NO_ENTRY
There is no frame information associated with the giving DWARF debug
context.
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_fde_cie_list_dealloc 3 ,
.Xr dwarf_get_cie_index 3 ,
.Xr dwarf_get_cie_of_fde 3 ,
.Xr dwarf_get_fde_at_pc 3 ,
.Xr dwarf_get_fde_instr_bytes 3 ,
.Xr dwarf_get_fde_n 3 ,
.Xr dwarf_get_fde_range 3 ,
.Xr dwarf_set_frame_cfa_value 3 ,
.Xr dwarf_set_frame_rule_initial_value 3 ,
.Xr dwarf_set_frame_rule_table_size 3 ,
.Xr dwarf_set_frame_same_value 3 ,
.Xr dwarf_set_frame_undefined_value 3
